Tuning control mechanism



Nov. 30, 1948. Y F'. w. FRINK ET AL 2,454,789

TUNING CONTROL MECHANISM Filed June 16, 3945 4 Sheets-Sheet 2 TTo/PNE'YNov. 30, 1948.

F. w. FRINK ET AL 2,454,789

TUNING CONTROL MECHANISM Filed June 16, 1945 4 Sheets-Sheet 3 ATTFNE'YNov. 30, 1948.

Filed June 16, 1945 F. w.v FRINK ETAL 2,454,789

TUNING CONTROL lMECHANISM 4 Sheets-Sheet 4 MWA,

Patented Nov. 30, 1948 runnin oNTRoL MECHANISM .Frederick i-Frink, tEastOrange, N. J .,rand Murray Kaplan,. `-Bro9klyn, N. Y., assignors toFedone .and Radio -Qorveratiom `New .atapi-,poration of Delawareimplication 1945, -Serial No. 599,908

This invention relates totuning controimechanisrnl andmo'reparticularly-Ktotunin'g .control mechanism for stopping'apanoramictuningtreceiver in a predeterminedtunedposition.

In panoramic tuned'receiverswherelnthe receiver is continuously tunedover a' frequency band or bands, it is often desird-to Vstop-the scannedtuning of the receiver at .a particular tuning positionrepresenting areceived ,station in order thatY the station may'4 betuned-,in moreprecisely for listening to orI sothatrdirctioninding may be accomplishedon this .fparticularfstation. In ,the panoramic tuningrecivers'generally some form of drive mechanism such asalmotor is usedto drive vthe tuning condensersof vvsuch a receiver to tunevthe systemover a Ldesiredtfrequency .band or Lbands'. .Iriordercto stopthevt'uning of the receivervin a `prede'termii'xdtunedposition, it istherefor desirable to provide some means .for stoppigthe 'nitor ata'..particla'r point in its rotation .sovthat lthe'freceiver.fwill'beproperly tuned to the `selected station.' ySuch panoramic 'tuningreceivers are r'generally provided with 'some form of visual indicator:which may, for example, `be a cathode '-ray `tuloe the sweep of whichrepresents the sweep through th'effrquency band. .Some-form 'lo'findexing n'ia'yibe provided adjustable over .the swep'tbandto a positioncorresponding to a signal indication;

Inv accordance with our invention fwe provide means for simultaneouslyadjusting astop mechanism together with theindexing' yindications sothat'the stop mechanism .will be positionedproperly to stop themotorlshould itbe `desiredlto listen in on the slectedjs'tation. .Forthis purpose, the motor .preferably is'islowed .down' or stpped prior tothemovement ofthestopmechamsm-nto a nnal stoppingrelationship so that.there .willrnot be too great a shock Qn themechanismwhen the motor Stopor detentcoqpraingwiththe :stop mechanism @emes irl-.centen ,therewithFurther.- more, whenA two r mereffreqveeCyhepia re beingseparatelycannedtin ,the Ielyer, `itis Lnec- Aessary that r,tllifcustib', ing'zczlianisizi he .A ,provided Kto stop the rotation '.0...t,.11`e.,`i0tor 'atlga .pointlc rw. SpendingtO the sleid,.steitienvitliinf .the lected frequencyhand.

In accordance ,with .our invention, we provide a mechanism which will`stopa 4i'x'iotm without producing undue strain 'on the shaftandwillstop the motor in the ldes'ire'd'tuingposition'inla'fselected oneof 'a plurality ffeque'ncy ban s. i

' n win be cie-ar that the'mechnisniivvel-have .designed while usefulprincipally-'inthe control of panoramic .tuning receivers'. mayube.of'mor'e generalcapplication and .may.serve to stopamotorin.a.desired.adjusted positionfor other purposesi. thanlthe .tuning of`a receiver arrangement. rIt saccordinglyan ooject of our Ainvention to,providea motorcontrolsystem whereby a nor- I'naLcontinuously drivenmotormay he stopped at a...predetermined Ipoint in its rotation.

-It .slaifurthenobject of .our invention to provde amotor control systemwherein .a stop mechan'ism is inserted. in thepath .of adetent rotatedby .the ;motorsubsequent yto a .stop ,controlaction fofithe motor iafter.which the motor .is .driven ,at a `lovvrgrate..of..speed. until.thedetent comesin contact with thefstop mechanism.

It ;isas.til1, further 4obj ect of ,our .invention .to .provide a .motor.control system for selectively stoppingithe..motor. in either, of two.chosen posi" tions', in ,which astop .means .provided .Witlrdia-.metrcallyiopposed ,stop v surfaces is .arranged .rotatably with.respect to the moto-r and. is made movable. into; the path .of aYdetent idrivenlcy the .motorin either, of two ydirections to stop.selectively themotor inthe .desired one of the two .selected positions.

Itis aJstilli-further `object of 4our invention to gnllbvide, inafrequency .scanning receiver, .means for stopping. thescanning of thereceiver. in a ,desired adjusted-ztuned position lhy .theselectiveinsertion of. astopvmechanism .into the path rof `the .driving..meansforthe .scanning receiver.

;It.is.a stllfurther objectof ourinvention-fto Iprovide, in a frequencyscanning receiver, means --for adjusting selectively said receiver `in adesired .tunedposition in one of a plurality of fre- `quencyh'ands 'byVselectively moving a selected :one .of .a plurality vof .stop Vsurfaces.into the' pat-h of .adetent Ydriven `loy the motor which normallyitunesfthe receiver through 'the scanned frequency bands.'

-It :isaI still further object of our invention to provide, inalfrequency scanning receiver, an inldexig indication and means `for.adjusting this indexing indication simultaneously Withvv .stop meansinacoar'se or line Vernier adjustment,y si- -niultaneouslywith movementofa stop means -to the desired relative position withrespect to the .tunedfrequency band over which .the receiver is scanned. .Whilewe `haveoutlined .brieiiy above the gen- `eral objects andieatures of ourinvention, a bet- .'.ter .understanding of these objects and features.'.may .be hadyfrom-.the .particular description there- .of vmade WithVr'eference -to the accompanying drawings, in which:

.-1.is a .blockschematic circuit and opera- Fig. 4 is a bottom view ofthe apparatus illustrated in Fig. 2;

Fig. 5 is an end view taken along line Ii-i of Fig. 2;

Fig. 6 is a perspective end view oi the control mechanism;

Fig. '7 is a sectional view taken along the line 'l-- of Fig. 2; and

Fig. 8 is a sectional view taken along line of Fig. 2.

Turning first to Fig. l, it is to be noted that this operational diagramis not intended to be complete in the mechanical details; its primarypurpose is to indicate iunctional relations less readily seen on theother views. In this Fig. l, a tunable receiver is shown at I havingcoupled thereto antennas 2 and 3 for receiving signal energy in an upperand a lower frequency band. Receiver I is tunable through; two frequencybands by means of a shait 4, driven by a motor ii. Motor 5 also drives ascanning disc l. The output of receiver I is coupled over a line l andthrough a coupler i5 to the vertical deflecting plates i! of a cathoderay oscillograph Ill. 'A pair of headphones II are also arranged to beenergized from the output of receiver I through listen switch I2.Control disc o is provided with a slot I3 rotated between a lamp i4 anda photocell I5 which serves to produce a square control wave which isapplied over line lo to receiver I. This control wave serves to switchthe rem ceiver between the bands received on antennas 2 and 3 for eachrevolution of the disc driven by motor 5. The control wave from theoutput of tube I5 is also applied over lines I I? and lli to coupler 8and then to the vertical deflecting plates 9 to produce a displacementof the tracing indication as shown at i8 and i9 representing the upperand lower frequency bands of the ren ceiver. The horizontal sweep of theindicator beam of oscillograph IIJ is provided by the shutter disc tthrough the medium of lamp 2d and photocell 2l. The output of photocell2i is applied over a line 22 to a sweep generator or amplifier 23, theoutput of which is applied across the horizontal delecting plates 24 ofindicator Ill. A third set of control means comprising a lamp 25 and aphotocell 2li is associated with disc t and serves over line 2l tocontrol the pro'- duction of indexing pulse in the indexing generator28. The output of the indexing generator 28 may be applied over acoupling line 23 and coupler 8 to the vertical deflecting plates il ofoscillograph I!) producing indicating bends or offsets 3l) and 3l in thesweeps i3 and Iii indi-- eating the upper and lower frequency bandsrespectively. A tuning knob 32 serves to rotate an indexing controlshaft 33 which serves to adjust the position of the offset indications3B; 3I through the adjustment oi indexing generator 28. This adjustmentmay be made in actual practice by adjustment of the rotary position oilamp 25 and cell 25 relative to disc Ii as shown by the extension ofshaits and 34.

Control knob 32 may normally be urged by a spring (not shown) inwardlyso as to move a control means 35, which may serve simultaneously asfrequency index, into contact with a clutch gear mechanism 35 looselymounted for rotation about shaft 33. Thus when knob 22 is released fromits normal position, gear 3b will normally be clutched to shaft 33. AVernier tuning knob 3'! serves to drive Vernier gear 33 to rotate shaft23 to provide the fine adjustment of tuning as indicated by scopeindicators 3o and 3l. Motor 5 also carries on its shaft 39 a stoppingdetent 4o having a stopping surface 4I. Detent it rotates with motor 5so that it at all times corresponds to the rotary position of the motor.A stop mechanism 42 mounted on a gear 43 is rotatably positionedrelative to the motor in accordance with the indexing adjustment by of agear 44 carried by shaft 33 meshing with gear 43. Thus, as the indexingindications 3o and Si are adjusted over the face oi the scope, stopmechanism 42 is adjusted in a rotary position with respect to the motor5 so that it will at all times be positioned with respect to therotation of the motor at a. tuning position indicated by indicators 3@and 3l respectively. Stop mechanism 42 carries two stop surfacesdiametrically opposed as shown at 45 and 46.

Under normal operating conditions, energy from power source 41 isapplied over a resistor arrangement 48, line 49, switch 50, switch liland smoothing filter 52 to motor 5 to drive the motor 5 at apredetermined speed during scan ning. When it is desired to stop themotor in a particular scanning position as represented by indications 30or 3l, a control lever 53 is moved into the upper or lower positiondependent upon which frequency band is to be observed. Upon movement oflever 53, control link 54 serves to close a switch 55 energizing relay56 so that switch I2 is closed and the listening device E i is put intothe circuit. Simultaneously, the movement oi lever 53 serves, by meansof a control linkage 5T, to move switch 5l) from its contact at line 49into contact with a line 53 serving to eiiectively short circuit thearmature 5A of the motor 5, iield 5B still being energized, and stop themotors rotation. When motor 5 has been stopped, linkage mechanism 59serves to move stop 2 in either of its two selective directions to bringstop surfaces 45 or 46 into the path of detent 4o, dependent upon whichirequency band has been selected. After a delay caused by the normaloperation of the linkage mechanism, linl: Eil through spring 6I servesto move switch contact 5I from its normal position into Contact withline 62 again energizing the motor with the energy produced in theyresistor 63 and the output oi power source 41. It will vbe noted,however, that in this case the voltage drop is low so that motor 5 willbe rotated at a slower speed. Motor 5 will then rotate at this reducedspeed until detent 40 comes into contact with the selected stop surface45 or 46 of stop mechanism 42 at which time the motor will be brought torest with the receiver 'I adjusted to position corresponding to indexingindications 30 or 3l dependent upon whether lever 53 has been moved upor down. It will be clear that by the use oi this type oi mechanism,motor 5 may be Stopped without undue shock to the equipment and may bestopped precisely inthe position indicated by the indexing indication.Should it be necessary then to adjust` the tuning of the receiver, forinstance to bring the-receiver more sharply into tune with the receivedsignal, then knob 31 may be rotated causing further rotation oi,` gear43 andl stopy mechanism 42. The motor, being energizedat a lower powerlevel, will follow up this tuning adjustment to adjust the tuning of thereceiver through the medium of' shaft 4. Simultaneously, the indexinglamp 25 and photocell 26'` will be also adjusted tov its correspondingnew position.

In yconnection with Figs. 2 through 8 inclusive, a more detaileddescription of the control mechanism is given. of shaft 4- and shaft 39,serves to drive the tuning condensers 'contained within housing 64;'when lever 53is'in its normal medium position. Movement of lever 53`upwards or downwards as shown in` Fig. 2 serves to rotate a disc 65:moving" link.

56 either'up or down causing linkv6`| to be movedj to the right.Movement of `link 51. causes' sliding of linkage mechanism' whichservesthrough the medium. of lever 59 tov close switch 50 serving toshort circuit the motor as indicated'inFig. 1. At the same time,movement of disc 65v through another link 'l0 rotates a` crank arm inone ofV two directions causing tensioning of spring `|2 or spring 13.depending upon whether lever 531is moved upwardly or downwardly.Springs. 7.2 and 13 are fastened on a disc 15 which is held fromrotation by means of a pin 1.6 carried on lever 1'|-. A spring 18normally tends to pull lever I1 into engagement in slot or notch 11a indisc 15. Springs '|2 and |3 are strong enough to overcome the action ofspring 'I8 so rotation of disc 'lil'will raise lever 11. A springcontrolledv lever 19 fitting over a pin 80 on lever Tl prevents thisfromhappening until linkage 68 has reached the end of its stroke. When thelinkage reaches the end of its stroke, however,v holding lever 19releases lever permitting it to move upwardly under the action of spring'l2 or '|3' and rotationof disc '|5. Rotation of disc 'l5 serves throughlinkages 8|, 82 and 83 to move a `carriage 84 (see Fig. 3) to the rightor left depending upon which direction lever 53 was moved. Carriage94`carries withit a push rod 85, pull r-od 86 which will` serve to rocka bell-crank lever 81 inthe same direction regardless ofthe direction oimovement of carriage 84. If' carriage 84` moves to the left, then pushrod 85 serves to push the lower end of bell-crank 81 into contact withswitch causing the circuit of motor 5' to be energized to drive themotor forward at a re'- duced speed as shown in Fig. 1. However, if thecarriage moves to the right then a hookA 88 on lever 85 serves to pullon the other end of lever 8T moving the bell-crank lever into contact toclose switch 5|'. It will thus be clear that regardless of the directionof' movement of carriage 84, switch 5| will be operated. The timeconsumed in operation of the linkage mechanism to move the carriage issuflicient for the motor to come toa complete stop before stopmechanism42" is moved into stopping position.

Prior to operation of switch 5|, however, stop mechanism 42 is movedinto the pathof the detent mechanism 40 driven by the motor. Operationof this may be more clearly,7 seen by reference to Fig. 6 together withFig. 3. Carriage 84 carries with it two fixed rods 89 and Sil-whichserve to move two spaced plates 9i and 92 either forward or backward.Between platesv 9| andA 92 is provided a crank pin- 93 coupled to-amutilated gear 94 which meshes with a rack 95 carried by stop mechanism42; Thus as the carriageis moved forward, mutilated gear 94: is rockedin one direction servingto move stop mechanism 42='intoposition forcontact with detent 40. When Motor 5, throughV the medium thecarriage'is moved in the opposite direction, the mutilated gear isrotated in the opposite direction and the stop mechanism is moved in theopposite direction into position for contact with detent 4|). Gear 43carrying stop means 42 .is preferably rotatable through 7 so that stopsurfaces 45' and 46 may be brought into stopping position anywherewithin one quarter ci the rotary position of shaft 39 and the coupledcondenser. The condenser covers both bands in; a single revolution asthe rotor is of the balanced 90 type. Thus the stop mechanism may bebrought into play anywhere within the scanning range covered by thesystem.

In order to assure a smooth drive for gear $3 upon rotation. of' knob32, the drive mechanism instead off taking a simple form shown in. Fig.l, consists in a` gear 96 fastened directly to the driving shaft andmeshing with two spur gears 98; These spur gears serve to rotate rods99, |90: tothe ends of which are fastened to two gears 44` meshing withdriven gear 43` as can be quite clearly seen in Fig. 3.

The control mechanism for the coarse and Vernier tuning of the apparatuscan be more clearly seen from Fig. 5. Here the knob 32 is shown providedwith the projecting portion 35 and ring gear 33. Gear 36 is provided' onits upper surface with a plurality of serrations |'0l into which a.projection on arm 35 ts as can be seen from Fig. 2. Arm 35 also carriesVwith it the pointer'mechanism I B2 lwhich cooperates with the tuningscale |03. When rapid coarse adjustment of the tuning index and stopmechanism is desired,lknob 32 is pulled outward disengaging 35 from theserrations i0! so that the apparatus may be rapidly rotated. The xedgear 9S is in engagement with the drive gears 9`|- and 98 to control thepositioning of the stop mechanism as previously described. When thecoarse adjustment has been achieved, knob 32 is released bringing arm35- into a corresponding notch in serrations |0| so that gear 35 willtend to turn the shaft. Then Vernier knob 3l is rotated turning the wormgear 39 to drive gear @Bf around slowly for the fine adjustment.

Turning now to Fig. 7, the operation of shutter G for the purpose ofproducing the various control waves can be more readily understood. Inthis arrangement the light I4 is arranged in xedspaced relation withrespect to disc 5 and opposite a slot i941 Slot |94 is semi-circular sothat* the light will shine half the time on the photocelri producingeiectively an electrical square wave output inv which the positiveportions are equal tothe negative or zero portions. For the saw-toothgenerator the lamp 29 shines throughone of two cut-out portions of thedisc as indicated at |65; |133. Thus, saw-tooth sweep voltages areproduced for alternate quadrants of a rotationV corresponding to thesweep voltages for the quarter revolution of the separatefrequencyfbands. The indexing is controlled' from lampisource 25 incooperation with the'masking portions HIT which serves to produce apulse voltage of a higher amplitude upon rotation of the shutter. Theinitiation point of this higher voltage may be changed by varyingrotatably the position of lamp 25 relative to the motor shaft. Thus theindexing voltage or indication may bc stepped around to the desiredposition as shown. I iamp'ZElis` driven simultaneously with the rotationofA gear 43l so that the indexing indication andthe position of thestopmechanism Will'at all timesproperly coincide.

From the foregoing, the particular apparatus shown in the illustrationsof the equipment may be readily understood. 7AWhile the apparatus hasbeen shown for use with a scanning receiver, it should be clear that thestop mechanism may 'ce utilized for any type of system wherein it isdesired to stop a motor at a predetermined position in its rotation.Furthermore, the disc and stop mechanism M need not rotate at the samespeed as the motor but may be stepped down o-r upwards by similar gearratios so that the two will rotate together. For the purpose of stoppingthe motor in proper indexing position, it is essential, however, thatthe stop mechanism be rotated relative to the tuning band sweep.

It is further clear from the description above that many alternatives tothe specic structural arrangement shown in connection with Figs. 2 to 8may be used if desired without departing from the scope of ourinvention. Furthermore, more than two stop positions may be provided ifdesired or a single stop position may be utilized. To those skilled inthe art, the modifica tions of the apparatus for achieving the variousfunctions will be clearly evident from the description of the foregoingapparatus.

It should therefore be clearly understood that the description given inconjunction with the specic apparatus shown is made merely by way ofillustration and is not to be considered as a limitation on ourinvention as set forth in the objects thereof and in the appendedclaims.

We claim:

1. En a frequency scanning receiver, means for adjusting said receiverto a desired tuned position, comprising a motor for scanning the tuningmeans of said receiver over a predetermined range, an indexing generatorcontrolled by said motor to provide an indexing indication of thedesired tuned position, means for adjusting said indexing indicationover said frequency range, a detent rotatable with said motor, a stopmeans rotatable with respect to said detent under control of said meansfor adjusting said indexing indication, and means for moving said stopmeans into the path of said detent to stop said motor in the tunedposition indicated by said index.

A receiver according to claim 1 wherein said last-named means comprisesmeans for stopping said motor prior to moving in of said stop means, andmeans for starting said motor at a reduced speed subsequent to movementof said stop means.

8. In a frequency scanning receiver scannable over two frequency bands,means for selectively adjusting said receiver to a desired tunedposition in either of said bands, comprising a motor for scan ning thetuning means of said receiver over said two frequency bands, an indexinggenerator controlled by said motor to provide an indexing indication ofthe desired tuned position, means for adjusting said indexing indicationover the frequency bands, a detent rotatable with said motor, a stopmeans having diametrically opposed stop surfaces rotatable with respectto said detent under control of said means for adjusting said indexingindication, and means for selectively moving said stop means in eitherof two directions into the path of said detent to stop said motorselectively in the tuned position with one of said frequency bandsindicated by said index.

4. A receiver according to claim 3 wherein said last-named meanscomprises means for stopping said motor prior to moving in of said stopmeans, and means for starting said motor at a reduced speed subsequentto movement of said stop means.

5. ln a frequency scanning receiver scannable over two frequency bands,means for adjusting said receiver to a desired tuned position in eitherof said bands, comprising a motor for scanning the tuning means of saidreceiver over said bands in succession during each revolution of saidmotor, an indexing generato-r controlled by said motor to provide anindexing indication of the desired tuning position in both said bands,means for adjusting said indexing indication simultaneously over bothsaid frequency bands, a detent rotatable with said motor, a stop meansprovided with diametrically related stop surfaces rotatable with respectto said motor under control of said means for adjusting said indexingindication, and means for selectively moving said stop means in eitherof two directions into the path of said detent to stop said motor in thetuned position within one of said bands indicated by said index.

6. A receiver according to claim 5 wherein said lastenamed meanscomprises means for stopping said motor prior to moving in of said stopmeans, and means for starting said motor in the same direction at areduced speed subsequent to moving of said stop means.

7. In a frequency scanning receiver operative over a frequency band,tuning means for tuning said receiver over said frequency band, a motordrive means for driving said tuning means through said band, an indexingmeans controlled by said motor for producing an indexing indication,means for adjusting said indexing indication simultaneously over saidfrequency band to indicate selected tuning positions, a detent meansrotated by said motor, a stop means having a stop surface movable intoengaging position with respect to said detent, means for rotating saidstop means with respect to said motor simultaneously with adjustment ofsaid indexing indication whereby said stop surface will be positionedwith respect to said motor in accordance with said indexing indication,and means for moving said stop surface into the path of said detent tostop said motor in tuned position corresponding to the position of saidindexing indication.

S. In a frequency scanning receiver operative over a frequency band,tuning means for tuning said receiver over said frequency band, a motordrive means for driving said tuning means thro-ugh said band, anindexing means controlled by said motor for producing an indexingindication, means for adjusting said indexing indication simultaneouslyover said frequency band to indicate selected tuning positions, a detentmeans rotated by said motor, a stop means have ing a stop surfacemovable into engaging position with respect to said detent, means forrotating said stop means with respect to said motor simultaneously withadjustment of said indexing indication. whereby said stop surface willbe positioned with respect to said motor in accordance with saidindexing indication, means for moving said stop surface into the path ofsaid detent to stop said motor in tuned position corresponding to theposition of said indexing indication, means for stopping said motorprior to movement of said stop means into stopping pou sition, and meansfor starting said motor after said movement of said stop means.

9. In a frequency scanning receiver operative over a frequency band,tuning means for tuning said receiver over said frequency band, a motortoi` simultaneously with adjustment -of said indexing indication wherebysaid .stop surface will be positioned with respect to said motor inVaccordance with Isaid indexing indication, means for moving said stopsurface l.into lthe .path of said detent to stop said motor inTtunedposition corresponding to the position .of said indexingindication, and means lfor coupling an audio signal reprcducer to theoutput of Asaid receiver upon movement of said stop mechanism. Y

l0. In a frequency scanning .receiver Ioperative over more than onefrequency band, tuning means .for successively tuning said receiver oversaid frequency bands, va motor drive means for driving said tuning meansthrough said successive bands for each .revolution of Vsaid motor, anindexing means controlled by 'said motor for vproducing an indexingindication, means for `adjusting said indexing indication simultaneouslyover said `frequency bands to indicate selected tuning positions, adetentrneans rotated by said motor, a stop means having-stop surfacescorrespending to said frequency bands movable selectively into engagingposition with respect to said detent, means for rotating said stop meanswith respect to said motor simultaneously with e. :Eustment of saidindexing indication whereby said stop surfaces will befpositioned 'withrespect to said motor in accordance withsaid indexing indication, andmeans ffor moving az'selected one of said stop surfaces into vthe pathofsaid Adetent to stop said moto-r in tuned position corresponding tothe position of .said indexing indication in the selected frequencyband.

1l. In a frequency scanning receiver operative over more than .onefrequency band, tuning means for .successively tuning said receiver oversaid frequency bands, a motor drive means for driving said tuning meansthrough said successive bands for each revolution, a display indicationin the output of said receiver yfor producing a visual display ofsignals in said frequency bands, an indexing means controlled by saidmotor for producing an indexing indication, means for adjusting saidindexing indication simultaneously over said display indicator forindication-of selected frequencies in said frequency bands, a detentmeans rotated by said motor, a stop means having stop surfacescorresponding to said jfrequency bands movable selectively into engagingposition with respect to said detent, means for rotating said stop meanswith respect to said motor simultaneously with adjustment of saidindexing indication whereby said stop surfaces will be positioned withrespect to said motor in accordance with said indexing indication, andmeans for moving a selected one of said stop surfaces into the path ofsaid detent to stop said motor in tuned position corresponding to theposition of said indexing indication in the selected frequency band.

2. In a frequency scanning receiver operative over more than onefrequency band, tuning means for successively tuning said receiver oversaid frequency bands, a motor drive means for driving jsaid `.tuninglmeans through said successive bands .for each revolution, a ldisplayindicator in the'ou'tput of Vsaid receiver for producing a visualdisplay of signals .in said frequency bands, an indexing meanscontrolled by said -motor for producing an indexing indication, meansfor adjusting said indexing indication simultaneously over said displayindicator forindication of selected frequencies in said frequency bands,a detent means rotated by said motor, :a stop means .having stopsurfaces .corresponding Vto said frequency bands movable.seloctivelyinto engaging position with respect to .said :'detent, meansfor rotating said stop means with resp-ect to said motor simultaneouslywith .adjustment of Said indexing indication whereby saidsstop surfacesywill be positioned with respect to said motor in accordance with saidindexing indication, and means for moving a selected oneof `saidjstopsurfaces into the path of said detent to stopsaid motor intunedpositioncorresponding to the position of said indexing indication in thesellected frequency band, means for stopping said motorl prior tomovement of said stop means into .stopping position, and :means forstarting said motor at `a lower rate after said movement of saidstopmeans.

l13. In a frequency scanning receiver operative over more lthan one.frequency band,.tuning means for successively tuning said receiver oversaid trequency bands, a motor drive 4means for driving said tuning means.through said successive bands foreach revolution, a display indicatorin the output of said receiver for producing a visual display of signals.in said frequency bands, an indexing means controlled by said motor forproducing an indexing indication, means fol-.adjusting said-indexingindication.simultaneously over said display indicato-r for indication ofselected frequencies ,in said frequency bands, a detent means rotated bysaid motor, `a stop means having .stop surfaces -corresponding .to saidfrequency bands movable selectively `into engaging position with`respect to said detent, means for rotating said stop :means withrespect to said motor simultaneously with adjustment of said indexingindication Wherebysaid stop surfaces will be positioned with respect-tosaid motorin accordance with said indexing indicationpmeans for moving aselected one of saidstop surfaces into the path of said detent to stopsaid motor in tuned position corresponding 'to the position of saidindexing indication in `the selected frequency band, and means operativeupon `movement of said stop means `.to :couple an audiosignalrepro-ducerto the output of said receiver.

'14.111 a frequency scanning receiver operative over two frequencybands, tuning means for `successively :tuning said receiver over saidfrequency bands, amotor drive means for driving said tuninganeansthroughsaid Vsuccessive'bands for each revolution, .a visual display indicatorfor producing separate .displays of received vsignals in said two4bands, anindexingmeans controlled by said motor for .producing anindexing indication, means for adjusting said indexing indication oversaid display indicator to indicate the tuning of a selected one of thereceived signal frequencies within said frequency bands, detent meansrotated by said motor, a stop means having di ametrically opposed stopsurfaces corresponding to said frequency bands movable selectively intoengaging position with resp-ect to said detent, means for rotating saidstop means with respect to said motor simultaneously with adjustment ofsaid 'indexing indication whereby said stop surfaces will be positionedwith respect to said motor in. accordance with said indexing indication,selective means for stopping said scanning in a selected one or saidbands, and means responsive to operation of said selective means formoving a selected one of said stop surfaces into the path of said detentto stop said motor in tun-ed posi-tion corresponding to the position ofsaid indexing indication in the selected frequency band.

15. In a frequency scanning receiver operative over two 'frequencybands, tuning means for suc- ;cessively tuning lsaid receiver over saidfrequency bands, a motor drive means for driving said tuning meansthrough said successive bands for each revolution, a visual display'indicator for producing separate displays of received signals in saidtvvo bands, an indexing means controlled by said motor for producing anindexing indication, means for adjusting said indexing indication oversaid display indicator to indicate the tuning of a:v

selected one of the received signal frequencies within said frequencybands, a detent means rotated by said motor, a stop means havingdiametrically opposed stop surfaces corresponding to said frequencybands movable selectively into engaging position with respect to saidd-etent. means for rotating said stop means with respect to said. motorsimultaneously with adjustment of said indexing indication whereby saidstop surfaces will -be positioned with respect to said motor inaccordance with said indexing indication, selective means for stoppingsaid scanning in a solected one ol said bands, means responsive to operation of said seiective means for Imoving a selected one of said stopsurfaces into the path of said datent to stop said motor in tunedposi-tion corresponding to the position of said indexing indication inthe selected frequency band, and means for maintaining said motorenergized at a lower level, whereby the motor will maintain said de'tentin contact with said stop mechanism upon further rotation oi said stopmeans.

16. In a frequency scanning receiver operative over two frequency bands,tuning means for successively tuning said receiver over said frequencybands, a motor drive means for driving said tuning means through saidsuccessive bands for each revolution, a visual display indicatcn` forproducing separate displays of received signals in said two bands, anindexing means controlled by said motor for producing an indexingindication, means for adjusting said indexing indication over saiddisplay indicator to indicate the tuning of a selected one o thereceived signal frequencies within said frequency bands, a detent meansrotated by said motor, a stop means having diametrically opposed stopsurfaces corresponding to said frequency bands movable selectively intoengaging position 'with respect to said detent, means for rotating saidstop means with respect to said motor simultaneously with adjustment ofsaid indexing indication whereby said stop surfaces will be positionedwith respect to said motor in accordance with said indexing indication,selective means for stopping said scanning in a selected one of saidbands, means responsive to operation of said selective means for movinga selected one of said stop surfaces into the path of said detent tostop said motor in tuned position corresponding to the position of saidindexing indication in the selected frequency band, means for stoppingsaid motor prior to said movement of said stop means, and means foragain starting said motor and maintaining said motor energized at alower level to cause rotation of said detent into engagement with theselected stop surface, and to maintain it in such engagement duringfurther rotation of said stop means.

17. In a frequency scanning receiver operative over more than onefrequency band, tuning mean for successively tuning said receiver oversaid frequency bands, a motor drive means for driving said tuning meansthrough said successive bands for each revolution of said motor, an inndexing means controlled by said motor for pro-- ducing an indexingindication, means for adjusting said indexing indication simultaneouslyover said frequency band to indicate selected tuning positions, a detentmeans rotated by said motor, a stop means having stop surfacescorresponding to said frequency bands movable selectively into engagingposition with respect to said detent, means for rotating said stop meanswith respect to said motor simultaneously with adjustment of saidindexing indication whereby said stop surfaces will be positioned withrespect to said motor in accordance with said indexing indication,selective means movable into selective positions D for stopping scanningin a selected one of said bands, means responsive to operation of saidselective means for moving a carriage mechanism in a selected direction,means responsive to movement of said carriage for successively stoppingsaid motor, moving the selected surfaces of said stop mechanism into thepath of said detent, and starting said motor at a reduced speed, wherebysaid motor Will be iinally stopped in the selected tuning positiondetermined by said index adjustment.

FREDERICK W. FRINl/I.

MURRAY KAPLAN.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,834,272 Enderwood Dec. 1, 19311,894,646 Trogner Jan. 17, 1933 1,906,709 Morin May 2, 1933 2,161,183Mastney June 6, 1939 2,307,514 King Jan. 5, 1943 2,333,848 Vette Nov. 9,1943 FOREIGN PATENTS Number Country Date 610,642 France June 14, 1926

